The present invention relates to a process for the production of a water-absorbing polymer structure, comprising the process steps:i) providing an untreated water-absorbing polymer structure having a degree of neutralization of at most 70 mol %;ii) bringing the untreated water-absorbing polymer structure into contact with an acidic component. In some embodiments, a Viterbi detector calculates branch metrics for a subset of the branches in a trellis diagram. Information is inferred about a presence of one or more participants in the call, based on a detection of the one or more participants by presence detection equipment associated with the conferencing endpoint;. The system may segregate pending deliveries into groups, with each group of deliveries assigned to a distinct automated collection point. The disclosure also relates to a process for determining the position of the distal end of a surgical instrument capable of passing through human or animal tissue.